Spark-plug for internal-combustion engines



F. W. SPRINGER.

SPARK PLUG FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED MAIL]. 191s.

1,399,166. Patented Dec. 6,1921.

2 SHEETS-SHEET I. Fig] 2 E93 -7 17 18 J7 I819 14/ -32 23 I a 24 23 15 20 d5 16' 26 25 16 ]6 F. W. SPRINGER.

SPARK PLUG FOR INTERNAL COMBUSIION ENGINES.

APPLICATION man MAR. 7, 1919.

1,399,166. Patented Dec. 6, 1921.

2 SHEETS-SHEET 2.

\ FRANKLIN WESLEY SPRING OT MINNEAPOLIS, MINNESOTA.

SPARK-PLUGIOB INTERNAL-COMBUSTION ENGINES.

Specification of Letters Patent.

Patented Dec. 6, 1921.

Application filed March 7, 1919. Serial No. 281,281.

To all whom it may concern.

Be it known that I, FRANKLIN WESLEY SPRINGER, a citizen of the United States, residing in Minneapolis, in the county of Hennepin and State of Minnesota, have invented a new and useful Improvement in Spark- Plugs for Internal-Combustion Engines, of which the followin is a specification.

My invention relates to spark plugs and has for .:s object to provide a spark plug havin means for rendering the occurrence V of the spark more positive and efi'ective. In

carrying out the objects of my invention I provide an auxiliary spark gap positioned near the principal spark gap and formed by the high tension terminal of the principal gap and a third terminal connected with a metallic body serving as a condenser and attached to the insulator of the plug. The auxiliary spark gap is made relatively short so that the air or gas in the vicinity of both gaps is ionized as the charge of current flows across the auxiliary gap into the condenser formed by the third .terminal prior to the occurrence of the spark and are in the main gap, thereby causing the space around the gap to be ionized and in a condition to be easily ruptured by the current producing the main or igniting spark which occurs directly afterward.

The full objects and advantages of my invention will be found in the detailed description and are particularly pointed out in the claims.

Figure 1 is an elevational view of a spark plug with a portion removed to show the application of myinvention' thereto. Figs. 2, 3, 4, 6, 8, and 9 are views similar to Fig. 1 of modifications of my invention. Figs. 5 and 7 are plan views of the spark plugs shown in Figs. 4 and 6 respectively.

My invention can be applied to practically all forms of spark plugs with very little modification or reconstruction of the same. An ordinary type of spark plug is shown in the drawings. An outer shell 10 adapted to be screwed into a cylinder by means of a threaded portion 11 1s formedhollow and is provided with an insulator 12 which is held in place by means of a bushing 13. A rod 14 passes through the insulator 12 and forms the high tension terminal of the spark plug gap. Another rod 15 is set into the edge of the shell 10 at 16 and forms the groundterminal of the gap. The ends 1'? and 18 of these rods are bent toward each other permitting the spark to jump between the same at 19.

My invention comprises an annular ring 20 which is slipped over the end of the insulator 12 and is held into a groove 21 formed on t 1e exterior of the insulator. A lug or car 22 extends from the ring 20 to the portion 18 of rod 14 and stops s ort of the same to provide a comparatlvely short spark gap at 23. It will be noted that this gap is positioned close to the ga 19.

The operation of the device is as follows: When the voltage between the high tension terminal 14 and the ground terminal 15 is sufficientlygreat a small uantity or charge of electrical energy flows rom the high tension terminal across the gap 23 through the car 22 and into the ring 20 which serves as a condenser. This gap 23 being considerably smaller than. the gap 19, the current passes through it first and the space, in and about it, becomes ionized as the charge passes through the gap, which leaves the gas in gap 19 in a similar condition. Since the state of ionization must exist before a spark can occur it can readily be comprehended that the process of ionization in ap 19 is provided for by means of the iiiw of current through gap 23 so that the flow of current through the same is easily started and at a comparatively lowvoltage, thus rendering the occurrence of the spark more positive and also making it possible for a spark to jump a longer gap. The spark terminals such as 17, 18, and 22 of Fig. 1 should preferably be rounded in form in order that the time-lagof the sparks may be as low as possible, although this is not a matter of vital importance in spark plug gaps where the gaps and terminals approximate the same dimensions. In the modification shown in Fig. 2 the condenser is formed by a single piece of wire 24 which is coiled preferably closely about the end of the insulator 12 and which terminates in a portion 25 extending toward the high tension terminal 18 to form a gap 23 the same as in the first form of the invention. A bead 26 formed on the end of the insulator 12 holds member 24 in place.

In Fig. 3 the high tension terminal 14 is shown straight throughout its length and the portion 17 of member 15 is made long enough to extend over to the member 14 forming the igniting gap at 27. With thls type of insulator a ring member 28 is used,

thereon by being rolled sewn.

ionization gap 23 in conjunction with 18,

same as the ring 20 in Fig. 1 which is rolled in place on the insulator 12 at 29. An ear 30 extends outward from ring 28 and is bent. toward rod 14 to form a small spark gap at 32 by means of which ionization is produced as in the other devices.

A slightly different form of the invention is shown in Figs. 4 and 5. This form resembles mostly the spark plug shown in Fig. 3 except that the high tension terminal 14 extends somewhat beyond portion 17 of terminal 15 at 34. The ring 28 and fingers 30 and 31 are identical with those of Fig. 3 except that the latter are made in one piece at their ends at 35, as best shown in Fig. 5, this end having a circular hole init through which the portion 34 of rod 14 extends to form an annular ionization gap, 36.

In Figs. 6 and 7 a ferrule 36 extendin on the interior and exterior of the end 0 insulator is fastened thereon by being rolled into a groove 37 similar to ring 20 in Fig. 1. In this particular spark plug the high tension spark terminal 14 is bent at its upper end into a U 38 which has its extreme portion 39 extending toward the edge 40 of ferrule 36 so as to form an ionization gap 41. Similarly the ground terminal 15 is bent in the form of a U at 42, with its extreme end 43 bent toward the ferrule 36. This end, however, falls short of the ferrule 36 some distance away from the same so that the ignition spark does not take place between this portion 43 of terminal 15 and the ferrule 36 but instead between said portion 43 and the corresponding portion 39 of terminal 14 which are spaced as shown in Fi 7 to form an ignition gap at 44.

nother form of the invention is shown in Fig. 8. Here the high tension terminal 14 is straight as in Fig. 3 but extends only a little beyond the edge of the threaded portion 11. The ground terminals in this spark plug comprise two members 45 and 46 issuing at right angles from the edge of the threaded portion 11 toward the high tension terminal 14 forming gaps 47 and 48.

A ring 49 is forced into the interior of the insulator 12 and has two prongs 52 and 53 issuing from -it which extend into the gaps 47 and 48 adjacent rod 14 to form ionizing gaps 50 and 51. When the circuit is first made ionization takes lace within the gaps 50 and 51 whereupon the spark immediately jumps from the terminal 14 to the terminals 45 or 46.

The last form of my invention is shown in Fig. 9. This differs from the other forms in the method of attaching the third terminal to the insulator and also in providing means whereby the ionization charge may be adjusted by varying the electrical capacity of the third terminal to-ground. In this form the third terminal 22, formin the is placed within the insulator in the form of wire 54 connecting with a screw terminal 55. If desired the length and hence the ca-' pacity of 54 may be increased by means of a wire 57 to which, in addition, may be attached a metallic late 59 and which may be placed in any esired position with respect to the engine 67, plug sleeve 10 or ground thus increasing or decreasing the capacity of the third terminal 5422 and the ionization charge in gaps 23 and in 19. The distances such as 61 and 63 of the third terminal to ground must of course always be relatively large as compared with the gaps 19, 23, and 65 so that no discharge of electrical energy may take place between any part of the third terminal and 10, the engine 67 or any other ground. (inc of the advantages of this plug is that the above adjustment may be made while the plug is in operation simply by moving the plate 59 to or from the ground as by means of a glass rod or any convenient insulator rod.

In all the forms of the invention the ionizing gap must be considerably shorter than the igniting gap so that the current will jump readily so as to ionize the gas in the main gap. For this latter purpose it can also be comprehended that the ionizing gap must be placed as close to the main gap as possible in order that the state of ionization be rapidly transferred to the main gap.

Th advantages of my invention are as follows: If through any irregularity of construction the ignition gap becomes so large that under ordinary conditions the spark would not jump, with my invention the gas would be in such a condition that the same could be broken down in spite of the increased gap thereb rendering the operation more positive. hen the gap is normal a more uniform spark is-obtained and total failure to jump is almost entirely eliminated. Such occasions frequently occur owing to variation in the contact make and break apparatus of igniting systems.

I claim:

1. A spark plug comprising an insulator and spark gap terminals forming an ignition spark gap, a metallic member carried by said insulator so as to form an ionizin gap in conjunction with one of the spar gap terminals in close proximity to the spark gap, and means for varying the capacity of said member.

2. A spark plug comprising an insulator and spark gap termina s forming an ignition spark gap, a conducting member passing through the insulator of the plug so as to form an ionizing gap in conjunction with one of the spark gap terminals in close proximity to. said spark gap and means for varying the capacity of the said member.

rmlxim 1mm srmcilh 

